Jin Se Yeon has had some difficult roles. She played a freedom fighter and Joo Won's tragic bride in "Bridal Mask." Then she played Kim Hyun Joong's childhood friend and ally in "Inspiring Generation." But now she will be playing two very different roles in the same upcoming drama.

In "Doctor Stranger" she will alternate between playing Song Jae Hee, a North Korean medical student and Han Seung Hee, a South Korean anesthesiologist. This will be very confusing for the character played by her co-star Lee Jong Suk. His character Park Hoon left Song Jae Hee behind in North Korea when he defected to the south. So, not only will he have to adjust to a dramatically different life than he led in North Korea but he will have to get used to working with a doctor who looks exactly like his first love. There's a mystery to their similar looks but it may take a while to uncover.

And it is a challenge, says the actress, to alternate between such different roles. Han Seung Hee is sophisticated and confident, with short stylish hair. Song Jae Hee is unsophisticated and innocent. She looks like a student.

"This is the first time I tried to play two roles, and it seriously isn't easy," said Jin Se Yeon. "It's very difficult to grasp all of the different aspects between the characters, such as tone, choice of words, and expressions. I work really hard while acting as Song Jae Hee to show young person is optimistic and innocent; while acting as Han Seung Hee, I have to somehow express the secrets that lie behind her eyes."

The drama mixes two genres, the medical drama and the political thriller. Genius doctor Park Hoon was kidnapped as a child and raised in North Korea. Now he's back in the south, working at Myung Woo University Hospital. But there's not just the usual jockeying for prestige and power within the hospital. The doctors also find themselves involved in a North Korean conspiracy to determine which doctors will operate on the South Korean prime minister. How involved is Han Seung Hee in this conspiracy? Jin Se Yeon is not saying.

"It's a challenge to play two characters, as I still have a lot to learn," said Jin Se Yeon. "It would be nice if people watch over me as I try. I will pay back my fans through working as hard as I can."

The first episode of Doctor Stranger" airs May 5.

Park Jin Woo wrote the script and Jin Hyuk will direct.